We obtained in vitro the DNA primed synthesis of alkaline phosphatase AP. The source of DNA is a phi 80 d phoA lac. The source of S30 is a phoA delta strain. The system can synthesize AP as well as Beta galactosidase (BG) which serves as control of efficiency of the system in the various conditions. The AP activity is due to AP dimer synthesized de novo in vitro. The in vitro synthesized subunits dimerize fast and efficiently. A positive element of control is introduced by S30 from phoB ion strain and not by S30 from phoB delta mutants. The in vitro system will be used to study the function of gene products responsible for positive control (phoB, phoRc) and negative control (phoR), the periplasmic proteins associated with phosphate transport (phoS, phoT) and other periplasmic proteins co-regulated with AP (polyphosphatase) and 3-polyphosphatases, P2, P3, P4b proteins co-factors like Pi and adenine (or a derivative of it) and assembly factors like membranes and Zn ions.